It is well known that in a broadcasting program output system, content data (the broadcasting programs) are stored beforehand in a video server, and then, under instruction from an automatic program output controller (APC), the content data are reproduced and sent on-air as required. With such on-air processing, typically an operation is carried out to check that the content data is in the proper order before broadcasting is carried out.
However, the image quality of the broadcasting has been improving drastically from high vision to full high vision (2K×1K), ultrahigh vision (4K×2K), and super high vision (8K×4K); and hence the size of the content data that are broadcast has been increasing dramatically. As the size of the content data has increased significantly, multi-channel broadcasting has been adopted for terrestrial broadcasting to BS (broadcasting satellite) broadcasting, and then CS (communication satellite) broadcasting. Consequently, the video server for handling the content data should have high capacity and should be adaptable to a multi-channel system.
Currently, such video servers are designed as a dual system to improve reliability by providing a backup for handling troubles during output (playback). However, when the video server implements a dual system design, its cost rises drastically. Consequently, smaller broadcasters such as local stations, local cable television stations, etc. face difficulty affording the dual system video recording/playback devices.
The content data managed by the video server are critical in program/CM broadcasting and error correction may be required. By incorporating a Reed-Solomon encoding/decoding function in the video server, it is possible to save the content data even when errors occur in a portion of the content data. But, with just the Reed-Solomon encoding/decoding function, a save or recovery may not be possible when trouble occurs with several storage units or at several locations storing the content data. Consequently, people have adopted a scheme whereby a RAID (redundant array of inexpensive disk) system is incorporated in the video server to guarantee the content data by using rebuild processing in the RAID system.
When there is an abnormality in a storage unit in the video server, this storage unit is exchanged and rebuild processing using the RAID function is carried out. If the rebuild subject is being recorded in the storage unit when the rebuild starts, the rebuild operation actually cannot be started. Consequently, when recording operations are being carried out continuously, a rebuild cannot be started, so it may take a long time until completion of the rebuild.
In addition, because the rebuild may take a long time, when a problem takes place in another storage unit, problems may occur in several storage units, and it may become impossible to read the content data. Since a read cannot be carried out, the rebuild cannot be performed, and thus the content data stored on the video server cannot be saved/recovered and may be lost.